Ion exchange

ABSTRACT

Dipolar organic compounds, such as ammonium bipolar carbamate, are used for exchanging and entraining ions in ion exchangers.

United States Patent 1 Siewertsz van Reesema Feb. 19, 1974 ION EXCHANGEInventor: Nikolaas Hendrik Siewertsz van Reesema, Rotterdamseweg 119,Delft, Netherlands Filed: June 14, 1971 Appl. N0.: 153,034

Foreign Application Priority Data June 19, 1970 Netherlands 7009021 US.Cl 210/30, 210/37, 210/38 Int. Cl 801d 15/04 Field of Search 210/24, 30,32

Primary Examiner-Samih N. Zaharna Assistant Examiner-[vars CintinsAttorney, Agent, or Firm-Brenner & Wray [5 7] ABSTRACT Dipolar organiccompounds, such as ammonium bipolar carbamate, are used for exchangingand entraining ions in ion exchangers.

2 Claims, No Drawings ION EXCHANGE V This invention relates to a methodof exchanging and entraining ions in ion exchangers and for theregeneration of such ion exchangers.

The method according to the invention is characterized by the use ofsolutions of dipolar organic compounds for the exchange and entrainingof the ions and for the regeneration of the exchangers.

There are dipolar organic compounds with a relatively large dipolemoment, or in other words, a relatively large distance between theelectrostatic charges.

I have now surprisingly found that these dipolar organic compounds arecapable of both displacing or exchanging the ions from anion or cationexchangers and carrying away the ions exchanged with the percolatingliquid.

When such a dipolar compound is represented by ABC, the chargedistribution can be indicated as ABC. In this formula, B suggests acertain necessary length between the two poles.

Furthermore, the exchange columns will be coded:

cc AC cation column and anion column.

When the two columns have been charge by percolation of a 4% NaClsolution, the following charge distributions are obtained:

l have found that ABC' can displace or exchange, but also that in thepercolating liquid the displaced Na" ion (in the case of CC) isimmediately attracted by another molecule in the percolating liquid andentrained This percolate can now beacidified with HCl and, byevaporation, followed by incineration, converted into NaCl, which can beeasily determined.

1 have found that with an adequate exchanging capacity and a properselection of the dimensions of the column'and moreover the requiredquantity of percolating *ABC", the quantity of NaCl cooresponds with thequantity of Na originally constituting the charge of CC.

One example of a suitable dipolar organic compound is a commerciallyavailable product sold under the name of Ammonii 'Carbonas" by ACFFarmaceutische Groothandel N.V. and N.V. Koninklijke PharmaceutischeFabrieken v/h Brocades-Stheeman & Pharmacia, both of Amsterdam, Holland.The product is claimed to have the approximate composition NH,HCO -NH CONH,, for'which reason it is often referred to as ammonium hydrogencarbonatecarbamate. Analysis has shown, however,that the indicatedformula cannot be correct, since the product does not exhibit thegeneration of carbon dioxide when a mineral acid is added. It dissolvesin water to a concentration of about 15 percent by weight with pH 9. Theproduct evaporates without decomposition when air is passed over thesolution at room temperature. The product can be easily prepared bypassing a stream of carbondioxide slowly through a 25 percent solution65 of ammonia in water at roomtemperature. The reaction is exothermic,and when the reaction is completed, the mixture cools off. Owing to theheat generated the reaction product is largely evaporated, and it iscondensed at colder places in crystalline form.

A possible formula which is in agreement with the dipolar character ofthe product is 5 This product is referred to herein and in theaccompanying claims as ammonium bipolar carbamate. Another example isbutene-2-al (croton aldehyde).

In this case there is a so-called overlap.

EXAMPLE I There was used 6.65 g insolubilized crystal humus (cf. DutchPat. application No. 7,009,020, describing the formation of epoxy groupsin crystal humus described in Dutch patent application No. 6,708,717,which mentions the crystal humus, ammonium humus crystallate; theproduct acts as a cation exchanger). The column was charged with a 4percent NaCl solution at pH 8 (approximately the pH of seat water). Thepercolating liquid was a solution of ammonium bipolar carbamate at pH 9(the equilibrium pH in water).

The exchange was effected in 3 periods, in each of which 2 X 10 cc of a14 percent solution of ammonium bipolar carbmate was percolated, hereagain represented by *ABC. The percolation was effected in the followingmanner.

First introduce 10 cc in a suction funnel, switch on a high-vacuum pump,suck through very rapidly, and suck off completely. Repeat thisimmediately with 10 cc without vacuum, and then again suck offcompletely. In this manner the so-called pore-NaCl can be neglected. Ofeach period of 2 X 10 cc, the NaCl content in the percolate wasdetermined by incinera' tion. One period lasted about 6 minutes.

There was found:

First period 0.43 g NaCl Second period 0.23 g NaCl Third period 0.03 gNaCl Theoretically, (3 X 58.5)/l080 X 6,65 1.08 g NaCl can be exchanged.

Consequently, in the first two periods, that is, in 12 minutes, (0.66 Xl0O)/1.08 61.1 percent is exchanged, whereafter there is apparently asteep decline in exchange.

It follows from the above that the exchanging capacity was amplysufficient. However, a relatively large suction funnel was used, so thatthe column was of low height, and the contact of *ABC with the ionexchanger was of short duration.

With the same quantity of cation exchanger, however, a much tallercolumn can be made, so that the exchanging capacity can be wellutilized, and the rate of throughflow can be increased, so that fullexchange can be realized in about 6 minutes.

EXAMPLE II Desalination of sea water and recovery of sea salt.

The apparatus consisted, for example, of a CC* and an AC, connected inparallel and disposed in vertical position. Initially these are in thecondition First phase.

Through the two columns the same quantity of sea water flows. Half ofthe total volume of seawater, containing Cl' ABC, is entrained from CCto a buffer reservoir, called CC buffer, and half of the total volume ofsea water containing Na CBA is entrained from AC to AC buffer.

Second phase.

Regeneration of the columns with ABC solution to re-instate thecondition CC ABC and AC CBA and also a discharge of Na TCBA from CC andof Cl ABC from AC* to an apparatus in which NaCl is recovered and *ABCis regenerated.

Third phase.

Discharge of sea water and ABC' from CC and AC buffers, the sea waterfrom the first phase from both columns being again passed through thecolumns. The percolate from both columns consisted of fresh watercontaining just ABC* in solution. It has been found that the ABC can berecovered in a simple manner by evaporation, leaving the water. Fourthphase.

The Na" and Cl still present in the columns is percolated with *ABC, andthe percolates C.| ABC- are re-introduced into the apparatus referred toin phase 2, in which *ABC is regenerated and sea salt is recovered. Inthe meantime the columns are again charges with *ABC for the nextcycle.Capacity of the columns.

It will be determined how large the columns should be to produceapproximately 400 tons of fresh water per hour.

The duration of a cycle can be supposed to be 40 minutes.

In 40 minutes, 40/60 X 400 ton 270 ton is produced. This quantity isproduced jointly by CC and AC, namely, half by each.

By CC alone, tons are produced in 40 minutes.

Approximately 135 tons of sea water are supplied and approximately 4/100X 135 tons 5.4 tons 4 percent NaCl solution are percolated in 40minutes.

The exchanging capacity of the crystal humus is given, because 1 kgcrystal humus can exchange 0,162 kg NaCl.

In order to exchange 5.4 tons NaCl with ABC, that is, with CC ABC5400/0162 X 1 kg exchanger 33,333 kg or 33.33 tons are required.

The material in CC consists of porous but hard granules having a volumeweight of about 0.8. Consequently, the volume is about 41.6 m.Accordingly, with a column 3 m tall, the cross-sectional area must beapproximately 14 m As stated before, the production per hour thenbecomes 400 tons of fresh water while the column have relativelymoderate dimensions.

1 claim 1. A process for the desalination of salt water by ion exchangewhich comprises passing salt water through a cation exchanging columnand an anion exchanging column, which columns have been charged with anaqueous solution of ammonium bipolar carbamate, passing the percolatefrom the cation exchanging column through an anion exchanging column andthe percolate from the anion exchanging column through a cationexchanging column, which columns have been charged with an aqueoussolution of ammonium bipolar carbmate, and recovering desalinated waterfrom the percolates thus produced.

2. Process according to claim 1, wherein the exchanging columns areregenerated by charging them with an aqueous solution of ammoniumbipolar carbamate.

2. Process according to claim 1, wherein the exchanging columns areregenerated by charging them with an aqueous solution of ammoniumbipolar carbamate.